Pulmonary artery and infra-coronary aortic bands have been placed in young miniature swine weighing four to six Kg. Swine were chosen for the experimental animals because: 1) Growth allows for the gradual development of ventricular hypertrophy. 2) At maturity the animals weigh 50 to 60 Kg, being comparable in size to humans. 3) Swine do not have epicardial collateral coronary arteries as do dogs. Myocardial morphology, ventricular function and regional coronary blood flow will be investigated.